Rotary face seal



Allg- 3, 1965 R. M. von-1K 3,198,529

ROTARY FACE SEAL Filed March 23, 1962 2 Sheets-Sheet l 2 Sheets-Sheet 2MM2 i.

l @WW Aug. 3, 1965 R. M. von-1K ROTARY FACE SEAL Filed March 2s, 1962United States Patent O 3,198,529 RTARY FACE SEAL Robert M. Voitik,Evanston, Ill., assigner to Continental Iliinois National Bank and TrustCompany of Chicago Filed Mar. Z3, 1952, Ser. No. 131,954

14 Claims. (Cl. 277-3) This invention relates to rotary seals forrestricting fluid leakage along shafts passing through relativelyrotatable housings and concerns, more particularly, a face seal type ofrotary seal.

A face seal is one which depends upon the rubbing contact of tworelatively rotating sealing faces for its sealing effect.Conventionally, a rotor is secured to a rotating shaft and a stator issecured to a housing through which the shaft passes. The rotor and thestator are formed with radial, annular sealing surfaces which abut toproduce a seal between the shaft and the housing. The sealing surfacesrub together as the shaft rotates and, thus, one surface or the .otheris normally formed of a bearing material.

When iiuid pressure is applied against a face seal, there is a certain`amount of penetration by the fluid between the sealing faces, theamount of penetration depending on the pressure of the fluid as offsetby the force urging the stator and rotor together. To avoid pop-off,Le., separation of the sealing faces, face seals are conventionallydisposed so that the iluid under pressure substantially einbraces thestator whereby the uid develops a force urging the sealing facestogether. In other words, the stator is placed in a deliberatelyunbalanced condition so that the development of uid pressure against theseal creates a greater force urging the stator against theY rotor thanis created in the :opposite direction by the penetration of fluidbetween the sealing faces.

As a result of the above unbalance, the magnitude of the force urgingthe sealing faces of the face seal into rubbing contact is directlyrelated to the pressure of the iiuid being sealed. Thus, the limitationsof excessive friction and undesirable wear have restricted face seals toapplications where the pressure of the fluid to be sealed is not great.As a practical matter, face seals cannot ordinarily be used to sealpressures above 350 or 400 p.s.i. Thus, while face seals are quiteeicient, their use in high pressure applications has not been possible.

In view of the above, it is the primary aim of the pres'- ent inventionto provide a novel face seal capable of effectively sealing uids at veryhigh pressures without excessive friction and wear. Seals of theinvention can be used in applications where the duid pressures reachvalues of 1,500, or even 2,500, p.s.i.

It is also an object to provide a face seal of the above type having agreatly increased service life whether the seal is utilized in high orlow pressure applications.

More specically, it is an object to provide a novel face seal in whichthe rubbing frictional contact of the sealing faces is self-limiting sothat an optimum pressure between the sealing faces can be establishedand will be maintained despite the magnitude of the fluid pressure .andvariations in the other factors normally alfecting sealing facepressure.

A further object is to provide a face seal of the above character whichis particularly reliable in that a substantial amount of fluid pressureunbalance can be provided to avoid inadvertent pop-off without theunbalance causing excessive frictional contact of the sealing faces asin a conventional seal.

Another object is to provide a face seal as characterized above which iseconomical and etlicient for high pressure applications since iteffectively replaces special sealing devices formerly required to handlehigh fluid pressures.

Patented Aug. 3, 1955 ICC It is still another object to provide a rotaryseal as described above which is -contained in a single package orlcartridge for convenience in handling and mounting.

Other objects and advantages of the invention will become apparent uponreading the following detailed description and upon reference to thedrawings, in which:

FIGURE 1 is an axial section of a rotary seal embodying the presentinvention;

FIG. 2 is a developed section taken in a plane indicated by the line 2-2in FIG. 1;

FIG. 3 is an axial section of a second type of seal also embodying theinvention;

FIG. 4 is a developed section taken in a plane indicated by the line 4-4in FIG. 3; and

FIG. 5 is a fragmentary section taken approximately along the line 5 5in FIG. 3.

While Ithe invention will be described in connection with certainpreferred embodiments, it will be understood that I do not intend tolimit the invention Vto those embodiments. On the contrary, I intend tocover all alternatives, modifications and equivalents as may be includedwithin the spirit and scope of the invention as defined by the appendedclaims.

yTurning first to FIGURE l, thereis shown ,a rotary seal embodying theinvention and arranged Ito restrict iluid leakage along a shaft 11 whichpasses through an opening 12 in a wall or housing 13. The shaft 11 andthe housing 13 are relatively rotatable and, in the illustra-tedassembly as in the typical practical case, the housing 13 is thestationary part and the shaft 11 rotates in f the direction of the arrow14.

The seal 10 is -a face seal and includes an annular rotor Ztl secured tothe shaft 11 by a clamp sleeve 21 which urges the rotor against ashoulder 22 formed on the shaft. An O-ring seal 23 isfinterposed betweentheshoulder 22 and the rotor so as to prevent fluid leakage between therotor and the shaft 11.

The rotor 20 includes a seal ring 25 defining a radially extendingsealing surface 26. The seal ring 25 is preferably formed of a bearingmaterial such as carbon.

Cooperating with the rotor 20 is an annular stator 30 surrounding theshaft 11 and having a radial sealing surface 31 facing, and in sealingengagement with, the rotor sealing surface 26. The stator 39 yis sealedto the housing 13 through a case or cup 32 which contains the p'arts ofthe seal 1d in a single package or cartridge. The cup 32 is Icloselyfitted with the opening 12 and is preferably sealed to lthe housing 13by an O-ring seal 33. The cup 32 is formed with an end wall 34 whichfaces and is axially spaced from the rotor 20. The stator is disposedbetwen the end wall 34 and the rotor and is sealed to the cup 32 by asecondary seal in the form of an O-ring 35 that is sandwiched betweenthe stator 30 and a circular flange 36 formed at the inner edge of theend wall 34.

f The stator 30 is thusl mounted so as to permit limited axial movementof the stator within the cup 32 toward `and away from the rotor 20. Inthe illustrated 'construction, a retaining ring 37 is snapped in theopen Vend of the cup 32 so as to overhang the rotor 2l) and complete theseal package.

The seal 10 is intended to function with fluid pressure moving againstthe seal from left to right in the direction of arrows'40. The sealedfluid, under pressure, thus acts against the secondary seal and theadjacent surfaces of the stator 30 so as to urge the sealing surfaces26, 31 together. While there is some penetration of the fluid beingIsealed between the sealing surfaces 26, 31, the greater opposing areaon the' opposite end of the stator 30 creates an unbalance so that thegreater the fluid pressure being sealed, the greater is the force urgingthe surfaces 26, 31 together. shaft 11 in the direction of the arrow 14,there is there- Upon rotation of thel fore rubbing contact between thesealing surfaces 26, 31

and, hence, the magnitude of the torque acting on the stator 30 isdirectly related to the pressure of the fluid being sealed.

In accordance with ythe invention, a portion of the torque acting on thestator 30 is converted into a force tendforce urging the stator 30against the rotor 20 is self-limitforce urging the stator 30 against therotor 20 is self-limiting. To generate this reverse acting or feedbackforce, the stator 30 is mounted for limited rotational movement relativeto the housing 13 under the urging of the torque exerted on the stator,and a plurality of axially inclined pins 45 couple the stator'and thehousing so as to shift the stator from the rotor 20 incident to thelimited rotational movement of the stator. In the preferredconstruction, six pins 45 are equally spaced peripherally about therotor 20. One end of each pin 45 is fitted in Ia socket 46 formed in apivot ring 47 which is secured to the cup 32 against rotation by a pairof radially projecting pins 48 received in slots 49 formed in the cup.The pivot ring 47 isblocked against axial movement by a frictionreducing thrust bearing 50 which is interposed between the rotor 20 andthe pivot ring 47.

The opposite ends of the pins 45 are fitted through openings 55 formedin a pin spacer 56 which is press ttedabout the periphery of the stator30. These pin ends bear against a flexible, radially extending washer 57which is fixed on the stator 30 by being tightly sandwiched between thepin spacer 56 and a lip 58 formed on the periphery of the stator.

To summarize quite briefly the operation of the seal 10, an increaseinthe pressure of the fluid being sealed tends to increase the force onthe stator 30 urging the sealing surfaces 26, 31 together. This acts toincrease the torque on the stator 30 resulting from the rotation of theshaft 11 and the rubbing frictional contact between the sealing surfaces26, 31. Since the stator 30 is mounted for limited rotational movement,this torque tends to rotate the stator in the direction that acts tostraighten the inclined pins 45, and thus the pins wedge the stator 30from the rotor 20. One end of each pin acts through the flexible washer57 against the stator and the opposite ends of the pins act against thepivot ring 47 and the interposed thrust bearing 50 against the rotor 20.

For establishing initial sealing contact between the sealing surfaces26, 31 before fluid pressure acts against the stator 30, a main spring60 of the annular wave form is sandwiched between the cup end wall 34and the flexible washer 57. To positively limit the range through whichthe pins 45 may tilt, a pin guide 61 is floatingly mounted between thepivot ring 47 and the pin spacer 56. The pin guide 61 is formed with aplurality of peripherally spaced, inclined openings 62 which freelyclear the pins 45 so long as the pins remain at their approximate properangles but which act as stops limiting the range through which the pinsmay tilt.

The preferred construction `also includes a preload spring 65 of anannular wave configuration which acts against the pivot ring 47 so as tourge it from the thrust bearing 50. The preload spring 65 is anchored byring 66 which is locked on the periphery of the stator 30. The effect ofthe preload spring 65 is to cause the seal 10 to act as a conventionalface seal until sufficient torque has been developed by the rubbingcontact between the sealing surfaces 26, 31 to rotate the stator 30 andtilt kthe pins 45 against the force of the preload spring so that thepins 45 act, through the thrust bearing 50, to wedge apart the rotor 20and the stator.

It is believed that a full appreciation of the operation of the seal cannow be obtained. Under static conditions and upon initial rotation ofthe shaft 11 relative to the housing 13 in the direction of the arrow14, the

main spring 60 urges the stator 30 against the rotor 20 so that asealing contact is maintained between the sealing surfaces 26, 31. Themain spring 60 does not exert enough force against the stator 30 todevelop sufficient torque on the stator to straighten the pins 45against the force exerted by the preload spring 65.

However, as the pressure of the fluid being sealed builds up and actsagainst the seal 10 in the direction of the arrows 40, the unbalanceddesign of the stator 30 causes the fluid pressure to urge the stator 30against the rotor with ever increasing force. This, in turn, increasesthe torque acting on the stator 30 until the pins 45 are straightenedsuliiciently to begin a wedging action tending to separate the rotor andthe stator. Thus, the torque developed at the sealing surfaces 26, 31 isfed back through-the pins 45 to limit the axial force directed againstthe stator 30;

This feedback force not only provides a direct mechanical load reliefacting in opposition to the fluid pressure forces urging the sealingsurfaces 26, 31 together, but also triggers a controlled amount ofpenetration of the fluid between the sealing surfaces. That is, bylessening the forces urging the stator against the rotor, a great eramount of fluid can penetrate between the sealing surfaces 26, 31 andthis penetration, of course, further serves to counterbalance the fluidpressure `forces urging the stator against the rotor. g l

As the direct mechanical load relief, and the amount of penetrationbetween the sealing surfaces, increases, the amount of friction betweenthe sealing surfaces 26, 31 and the resulting torque on the stator 30decreases so as to reduce the feedback force. The forces acting on thestator thus tend to balance out and tests have indicated that, as aresult of this balanced feedback action, a seal exemplified by the seal10 can effectively operate in applications requiring the sealing offluid at pressures ranging from 1,500 to 2,500 p.s.i.

Since the rotor 20 and the thrust bearing 50 move with the shaft 11,axial or slight eccentric movement of lthe shaft does not affect theabutment against which the pins 45 react and, hence, the angulardisposition of the pins and the feedback force which they develop arenot affected by axial shifting movement or slight eccentricity of theshaft. Furthermore, the radially extending flexible washer 57 provides aslight resilience between the ends of the pins 45 and the stator 30which tends to equalize the forces exerted by the several pins so that,in effect, the effective lengths of the pins are made uniform.

It has been found that the proper angle of inclination Vof the pins 45relative to the axis of the shaft 11 and the -seal 10 is within therange 15 to 20. At this angle, effective feedback is obtained withoutdanger of the pins overcentering and, at this approximate angle, theinclined pin arrangement embodied in the seal 10 very efficientlyconverts torque into an axial force.

It should also be mentioned that because of the existence of thefeedback force developed by the inclined pins 45, the stator 30 can bedesigned with a greater amount of fluid pressure unbalance than mightnormally be desirable. That is, the stator can be Sealed to the cup 32at a point which will cause an appreciable amount of fluid pressureunbalance tending to urge the stator against the rotor. This amount ofunbalance, relatively high as compared to standard face seals, minimizesthe danger of inadvertent pop-off and loss of sealing effectivenesscaused by sudden separation of the sealing faces 26, 31.

Turning next to the embodiment of the invention shown in FIGS. 3 to 5,parts corresponding to those described in connection with the seal 10have been given identical reference numerals with the distinguishing suffix"a added. Thus, there is shown in FIG. 3 a rotary seal 10a arrangedto restrict fluid leakage along a shaft 11a through an opening 12a in ahousing 13a. The shaft 11a and the housing 13a are relatively rotatablewith it being assumed that the shaft rotates relative to the stationaryhousing.

The seal a includes a rotor 20a secured to the shaft 11a by a clampsleeve 21a which locks the rotor against a shoulder 22a formed on theshaft 11a. An O-ring seal 23a is interposed between the shoulder 22a andthe rotor. The rotor a includes a seal ring 25a having a radiallyextending sealing surface 26a.

Cooperating with the rotor 20a is a stator 36a having a sealing surface31a facing and in engagement with the sealing surface 26a. The stator36a is sealed to the housing 13a through a cup 32a which surrounds theseal parts and deines a single cartridge. The cup 32a is mounted in theopening 12a and is sealed to the housing by an O-ring seal 33a. Thestator 36a is disposed between the rotor 20a and an end wall 34a forminga portion of the cup 32a. A secondary O-ring seal 35a is interposedbetween the stator a and a cylindrical flange 36a formed at the innerend of the end wali 34a. A retaining ring 37a holds all of the parts ofthe seal 10a within the cup 32a.

To generate the reverse acting or feedback force of the invention in theseal 10a, the stator 36a is mounted for limited rotational movementunder the urging of the torque developed by relative rotation of thesealing surfaces 26a, 31a, and a cam and cam follower connection couplesthe stator Sila and the housing 13a for shifting the stator from therotor 20a incident to the limited rotational movement. In the exemplaryconstruction, a cam ring 70 is secured against relative rotation withinthe cup 32 by a pair of oppositely extending pins 48a which iit withinaxially extending slots 49a formed in the periphery of the cup 32a. Thecam ring 70 is formed with a pair of diametrically opposed, shallow,symmetrical cam surfaces 71 which face the cup end wall 34a. A frictionreducing thrust bearing Sita is interposed between the cam ring 70 andthe rotor 20a to block axial movement of the cam ring.

The cam followers take the form of miniature ball bearings 72 which rideon the cam surfaces 71 and are secured by posts 73 to a gimbal ring 74.The gimbal ring '74 is pivoted on the stator 36a by a pair of pins 75secured in the periphery of the stator so as to lie within yoke slots 76formed in the gimbal ring 7d. The disposition of the pin 75 and theslots '76 define an axis for pivoting the gimbal ring 74 on the stator3tlg that is substantially atY right angles to a line through the camfollower posts 73. There is thus provided a universal connection betweenthe cam ring 70 and the stator 39a which permits approximately a 5 tiltbetween the cam ring and the stator. This universal, tilting connectionaccommodates the seal 19a for effective operation with a rotor whosesealing surface is somewhat tilted with respect to the axis of the seal.The yoke slots 76 facilitate easy assembly and disassembly of the sealparts.

To establish initial contact between the sealing surfaces 26a, 31a, anannular wave spring 66a is interposed between the stator 30a and the cupend wall 34a.

Operation ofthe seal 10a is virtually identical to the operation of theseal 1G described above. Upon development of a force urging the stator30a towards the rotor 20a, a torque is Vexerted on the stator by thefrictional engagement between the sealing surfaces 26a, 31a. This torquecause's a slight rotational movement of the stator 30a in the directionof rotation of the shaft 11a, with the result that the gimbal ring 74 isrotated with the stator and the cam followers 72 ride along the camsurfaces-71 so as to urge the gimbal ring, and thus the stator 30a, awayfrom the rotor 20a. There is thus developed a feedback force resultingfrom the frictional engagement at the sealing surfaces 26a, 31a. Theselflimiting quality and effect of this feedback force is as describedabove in connection with the seal 1t).

VIt is of Significance to note, however, that the symmetricalconformation of the cam surfaces 71 allows the seal 10a to function withequal effectiveness upon rotationof the shaft 11a relative to thehousing 13a in either direction. That is, a feedback force is developedupon relative rotation between the gimbal ring 74 and the cam ring 70 ineither direction since the lcam surfaces 71 are symmetrical. The thrustbearing 50a permits the seal Irda to operate effectively upon slightaxial movement of the shaft 11a relative to the housing 13a, and underconditions where the shaft rotates with a slight eccentricity relativeto the housing. As previously discussed, the universal connectionbetween the cam ring 70 and the stator 30a allows the seal to operatewith complete effectiveness even in view of a slightly tilteddisposition of the rotor sealing surface 26a relative to the axis of thestator 30a.

It wiil be appreciated, of course, that seals of the present inventionnot only may be used in applications where the fluid pressure reacheslevels heretofore much too high for a face type seal, but that thefeedback action of the present seals greatly increases the service lifeof;x

the seals whether utilized in high or average pressure applications.That is, the feedback force tends to minimize the frictional engagementbetween the sealing surfaces so that wear is controlled.

ln the following claims, the terms rotor and stator have been usedsimply for convenience in identification and with no intent to implythat the rotor and the parts on which it is mounted always rotate whilethe stator and the parts to which it is secured are always stationary.Relative rotation is what is required, and hence the claimed stator mayrotate relative to the claimed rotor as well as vice versa.

I claim as my invention:

1. A rotary seal for restricting iiuid linkage along a shaft passingthrough a relatively rotatable housing comprising, in combination, anannular rotor secured to said shaft and defining a sealing surface, anannular stator surrounding said shaft and 4having a sealing surfacefacing `said rotor sealing surface, means for establishing a iiuid sealbetween said stator and said housing, means for urging said surfacesinto sealing engagement so that relative rotation between said rotor andsaid stator creates a torque tending to rotate the stator relative tosaid housing, said stator being mountedfor limited rotational movementrelative to said housing under the urging of said torque, and meansincluding a pair of elements for converting relative rotation of saidelements into relative axial movement of the elements, said means beinginterposed between said stator and Asaid rotor with one of said elementsbeing coupled for rotation with said stator andthe other of saidelements acting axially against said rotor.

2. A rotary seal for restricting uid leakage along a shaft passingthrough a relatively rotatable housing comprising, in combination, Vanannular rotor 'secured to :said shaft and defining a sealing surface, anannular stator surrounding said shaft and having a sealing surfacefacing said rotor sealing surface, means for establishing' a liuid sealbetween said stator and said housing, means for urging said -surfacesinto sealing engagement so that relative rotation between said rotor andVsaid stator creates a torque tending to rotate the stator relative tosaid housing, said stator being mounted for limited rotational movementrelative to said housing under the urging of said torque, and aplurality of peripherally spaced, axially inclined pins coupling .saidstator and said housing Yfor urging the stator from said rotor incidentto 'said limited rotational movement.

3. A rotary seal for restricting iiuid leakage `along a shaft passingthrough a relatively rotatable housing comprising, in combination, .anannular rotor secured to said shaft and defining a sealing surface, anannular stator surrounding said shaft and having a sealing surfacefacing said rotor sealingsurface, means for establishinga uid sealbetween said stator and said housing, means for urging said surfacesinto sealing engagement so that relative rotation between said rotor andsaidstator creates a torque tending to rotate the stator relative tosaid housing, said stator being mounted for limited rotational movementrelative to said housing under the urging of said torque, and a cam anda cam follower on said cam coupling said stator and said housing forurging the stator from said rotor incident to said limited rotationalmovement.

4. A rotary seal for restricting fiuid leakage along a shaft passingthrough a relatively rotatable housing comprising, in combination, anannular rotor secured to said shaft and defining a radially extendingsealing surface, an annular stator surrounding said shaft and having aradially disposed sealing surface in contact with said rotor sealingsurface, means for establishing a iiuid seal between said stator andsaid housing so that duid under pressure on one lside of said contactingsurfaces develops a uid force urging said surfaces together with theresult that relative rotation between the rotor and the stator creates atorque tending to rotate the stator relative to the housing, said statorbeing mounted for limited rotational movement relative to said housingunder the urging of said torque, and means including a pair of elementsfor converting relative rotation of said elements into relative axialmovement of the elements, said means being interposed `between saidstator and said rotor with one of said elements being coupled forrotation with said stator and the other of said elements acting axiallyagainst said rotor, whereby the effect of said fluid force in urgingsaid surfaces together is self-limiting. v

S. A rotary seal for restricting fluid leakage along a .shaft passingthrough a relatively rotatable housing comprising, in combination, anannular rotor secured to said shaft and defining a radial sealingsurface, an annular stator being sealed to said housing and having asealing surface facing said rotor sealing surface, a pivot ring securedagainst rotation and axial movement relative to said housing and havinga plurality of annular spaced sockets, and a plurality of pins eachhaving one end fitted into one of said sockets and the other end fixedrelative to said stator so that relative rotation between said sealinglsurfaces tends to rotate said stator in a direction straightening saidpins.

6. A rotary seal for restricting fluid leakage along a vshaft through arelatively rotatable housing comprising,

in combination, an annular rotor secured to said shaft and defining aradial sealing surface, an annular stator being sealed to said housingand having a sealing surface facing said rotor sealing surface, a pivotring secured against rotation relative to lsaid housing and having aplurality of annular spaced sockets, a friction reducing thrust memberinterposed between said rotor and said pivot ring, a plurality of pinseach lhaving one end fitted into one of said sockets and the other endfixed relative to said stator so that relative rotation between saidsealing lsurfaces tends to rotate `said stator in a directionstraightening said pins, a main spring acting against said stator tourge said faces into engagement, and a preloa-d spring acting againstsaid pivot ring to urge it axially from said thrust member.

7. A rotary seal for restricting fiuid leakage along a shaft passingthrough a relatively rotatable housing comprising, in combination, anannular rotor secured to said shaft and defining a radial sealingsurface, an annular cup sealed in said housing and surrounding saidrotor, said cup having an end wall facing and axially spaced from saidrotor, an annular stator disposed between said rotor and said end wall,said stator being sealed to said cup and having a sealing surface facingsaid rotor sealing surface, a pivot ring secured against rotation andaxial movement within said cup and having a plurality of annular spacedsockets facing said end wall, and a plurality of pins each having oneend fitted into one of said sockets and the other end fixed relative tosaid stator so that relative rotation between Isaid sealing surfacestends t0 rotate said stator in a direction straightening said pins.

8. A rotary seal for restricting fiuid leakage along a shaft passingthrough a relatively rotatable housing comprising, in combination, anannular rotor secured to said shaft and defining a radial sealingsurface, an annular stator being sealed to sa-id housing and having asealing lsurface facing said rotor sealing surface, a pivot ring securedagainst rotation and axial movement relative to said housing and havinga plurality of annular spaced sockets, a friction reducing thrust memberinterposed between said rotor and said pivot ring, a flexible radiallyextending member secured to lsaid stator, a pin spacer secured to saidstator and having a plurality of openings corresponding to but annularlyspaced from said sockets, a plurality of pins each having one end fittedinto one of said sockets and the other end passing through the,corresponding one of said openings into contact with said flexiblemember so that relative rotation between said sealing surfaces tends torotate said stator in a direction straightening said pins, and a preloadspring acting against said pivot ring to urge it axially from saidthrust member.

9. A rotary seal for restricting fluid leakage along a shaft passingthrough a relatively rotatable housing comprising, in combination, anannular rotor secured to said shaft and defining a radial sealingsurface, an annular cup sealed in said housing and surrounding saidrotor, said cup having an end wall facing and axially spaced from saidrotor, an-annular 4stator disposed between said rotor and said end wail,said stator being sealed to said :cup and having a sealing surfacefacing said rotor sealing surface, a pivot ring secured against rotationwithin said cup and having a plurality of annular spaced ysockets facingsaid end wall, a friction reducing thrust member interposed between saidrotor and said pivot ring, a flexible radially extending member securedto said stator, a pin spacer secured to said .stator and having aplurality of openings corresponding to but annularly spaced from saidsockets, and a plurality of pins each having one end fitted into one ofsaid sockets and the other end passing through the corresponding one of4said openings into contact with said exible member so that relativerotation between said sealing surfaces tends to rotate said stator in adirection straightening said pins.

10. A rotary seal for restricting fluid leakage along a shaft passingthrough a relatively rotatable housing comprising, in combination, anannular rotor secured to said shaft and defining a radial Sealingsurface, an annular stator being sealed to said housing and having asealing surface facing said rotor sealing surface, a cam` ring having apair of diametrically opposed shallow symmetrical cam surfaces, afollower ring having a pair of cam followers disposed in engagement withrespective ones of said cam surfaces, means mounting said cam ring andfollower ring in force transmitting relation to said stator so thatrotation of the stator causes said surfaces and followers to urge thestator from said rotor, said means including a pivotal gimbal connectionpermitting rotation upon an axis substantially at right angles to a linethrough ,said cam followers, and a spring interposed between said endwall and said stator to urge said faces into engagement.

11. A rotary seal for restricting uid leakage along a shaft passingthrough a relatively rotatable housing comprising, in combination, anannular rotor securedrto said shaft and defining a radial sealingsurface, an -annular cup sealed in said housing and -surrounding saidrotor, 'said cup having an end wall facing yand axially spaced from saidrotor, an annular stator disposed between said rotor and said end Wall,said stator being sealed to said cup and having a sealing surface facingsaid krotor sealing surface, a friction reducing thrust member disposedwithin said cup against said rotor, a cam ring disposed in said cup andhaving a pair of diarnetrically opposed shallow symmetrical camsurfaces, a

pair of cam followers disposed in engagement with respective ones ofsaid cam surfaces, said cam ring and said cam followers being interposedin force transmitting relation between said thrust member and saidstator, and a spring interposed between said end wall and said stator tourge said faces into engagement.

12. A rotary seal for restrict-ing iiuid leakage along a shaft passingthrough a relatively rotatable housing comprising, in combination, anannular rotor secured to said shaft and defining a radial sealingsurface, an annular cup sealed in said housing and surrounding saidrotor, said cup having an end Wall facing and axially spaced from saidrotor, an annular stator disposed between said rotor and said end Wall,said stator -being sealed to said cup and having a sealing surfacefacing 'said rotor sealing surface, a cam ring secured against rotationwithin said cup and having cam surfaces facing said end wall, a frictionreducing thrust member interposed between said rotor and said cam ring,a cam follower connected to said stator and disposed in engagement withsaid cam Surfaces, and a spring interposed between said end wall andsaid stator to urge said faces into engagement.

13. A rotary seal for restricting uid leakage along a shaft passingthrough a relatively rotatable housing comprising, in combination, anannular rotor secured to said shaft and defining a rad-iai sealingsurface, an annular stator being sealed to said housing and having asealing surface facing said rotor sealing surface, a cam ring sccuredagainst rotation relative to said housing and having a pair of-diametrically opposed, shallow, symmetrical cam surfaces, a frictionreducing thrust member interposed betwe-en said rotor and said cam ring,a -gimbal ring surrounding said stator and carrying a pair of camfollowers in engagement with said cam surfaces, means defining a pivotalconnection between said gimbal ring and said stator permitting rotationabout an axis lsubstantially at right angles to a line through said camfollowers, and a spring interposed between said end wall and said statorto urge said faces into engagement.

f4. A rotary seal for restricting iiuid leakage along a shaft passingthrough a relatively rotatable housing comprising, in combination1 an`annular rotor secured to said shaft and dening a rad-iai sealingsurface, an annular cup sealed in said housing and surrounding saidrotor, said cup having an end wall facing and axially spaced from saidrotor, an annular stator disposed between said rotor and said end wall,said stator being sealed to said cup and having a sealing surface facingsaid rotor sealing surface, a cam ring secured against rotation withinsaid cup and having a pair of diametrically opposed, shallow,symmetrical cam surfaces facing said end wall, a friction reducingthrust member interposed between said rotor and said cam ring, a gimbalring surrounding said stator and carrying a pair of cam followers inengagement with said cam surfaces, means defining a pivotal connectionbetween said gimbal ring and said stator permitting rotation about anaxis substantially at right angles to a line through said cam followers,and a spring interposed between said end wall and said stator to urgesaid faces into enga-gement.

References Cited by the Examiner UNITED STATES PATENTS 3,052,475 9/62Carfagna 277-93 LEWIS l. LENNY, Primary Examiner. EDWARD V. BEN HAM,Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent Noc3,198,529 August 3, 1965 Robert M., Voitik It is hereby certified thaterror appears in the above numbered patent requiring correction and thatthe said Letters Patent should read as corrected below.

In the grant, lines 2 and 3, and lines 12 and 13, and in the heading tothe printed specification, lines 3 and 4, name of assignee, for"Continental Illinois National Bank and Trust Company of Chicago", eachoccurrence, read Continental Illinois National Bank and Trust Company ofChicago, as trustee Signed and sealed this 18th day of January 19665(SEAL) Attest:

ERNEST W. SW'IDER EDWARD I. BRENNER Attesting Officer Commissioner ofPatents

1. A ROTARY SEAL FOR RESTRICTING FLUID LINKAGE ALONG A SHAFT PASSINGTHROUGH A RELATIVELY ROTATABLE HOUSING COMPRISING, IN COMBINATION, ANANNULAR ROTOR SECURED TO SAID SHAFT AND DEFINING A SEALING SURFACE, ANANNULAR STATOR SURROUNDING SAID SHAFT AND HAVING SEALING SURFACE FACINGSAID ROTOR SEALING SURFACE, MEANS FOR ESTABLISHING A FLUID SEAL BETWEENSAID STATOR AND SAID HOUSING, MEANS FOR URGING SAID SURFACES INTOSEALING ENGAGEMENT SO THAT RELATIVE ROTATION BETWEEN SAID ROTOR AND SAIDSTATOR CREATES A TORQUE TENDING TO ROTATE THE STATOR RELATIVE TO SAIDHOUSING, SAID STATOR BEING MOUNTED FOR LIMITED ROTATIONAL MOVEMENTRELATIVE TO SAID HOUSING UNDER THE URGING OF SAID TORQUE, AND MEANSINCLUDING A PAIR OF ELEMENTS FOR CONVERTING RELATIVE ROTATION OF SAIDELEMENTS INTO RELATIVE AXIAL MOVEMENT OF THE ELEMENTS, SAID MEANS BEINGINTERPOSED BETWEEN SAID STATOR AND SAID ROTOR WITH ONE OF SAID ELEMENTSBEING COUPLED FOR ROTATION WITH SAID STATOR AND THE OTHER OF SAIDELEMENTS ACTING AXIALLY AGAINST SAID ROTOR.